1. Field of the Invention
An optical viewfinder is commonly seen on both film and digital cameras. The viewfinder assists the operator of a camera in pointing and framing an object to be focused on the image plane of a digital CCD or CMOS sensor for digital processing. Digital cameras, cell phones cameras or small imaging devices that requiring short profiles are possible examples of applications in which the subject invention can be employed.
2. Description of Related Art
Conventional viewfinders have at least two separate lens elements (such as the Galilean type) with appropriate spacing between the elements. There are several significant problems with existing viewfinders. The first problem is that the overall length of existing viewfinders makes them unsuitable for compact cameras such as the ones used in PDA and cell phones. The second problem is that it is costly and difficult to provide a reticle for aiming purpose with existing two element viewfinders. A multi-element viewfinder with one or more optical elements may also include one or more prisms. The lens material, the number of lenses, the prescription for each lens or prism element and the distance at which each lens element is positioned along the optical axis in front of the viewing port establishes the thickness and contributes to the cost of the viewfinder.